Peters



(N0 Modei.)

E I. WARNER.

MULTIPLE SWITCH BOARD SYSTEM OF TELEPHONE EXGHANGES. 7

No. 356,859. Patented Feb. 1, 1887.

Nv PETEBS. Prow-Umognpher, Wuhinflon. D. l;

UniTn STnTns PATENT ERNEST P. W'ARNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE ES ER-N ELECTRIC COMPANY, OF SAME PLACE.

lllULTlPLE-SWlTCH-BOARD SYSTEM OF TELEPHONE-EXCHANGES.

SPECIFICATION forming part of Letters Patent No. 355,859, dated February 1, 1837.

Application filed November 6, 1886.

To all whom it may con-corn.-

Be it known that I, Ennns'r P. WARNER, a citizen of the United States, residing at Chicago, in the county of Cool: and State of lilinois,huve invented a certain new and useful I mprovement in illultiple-SwitchBoard Systems of Telephone-Exchanges, of which the follow ing is a full, clear, concise, and exactdescription, reference being bad to the accompanying i0 drawing, forming it part of this specification.

My invention relates to multiple switchboard systems of telephone-exchunges, and more particularly to that system in which the telephone-lines, after passing through their spring-jacks and other apparatus, (u-e connccted through cords and plugs to ground, a cord and plug thus beingincluded in the ground portion of each of the lines. The cords are distributed otthe different boards, prcfcrubly in the some manner as the individual annoucietors, so that when a, call comes in from any line the cord of said line will be at the some board as the individual ennunciutor which indicu-tes the call.

The operator finds out by listening at his telephone what connection is wanted, and then inserts the plug of the calling subscriber in the switch of the subscriber called, and, throwing battery to line, summons the called snb- 3c scriber. The plug of the calling subscriber having been inserted in the switch of the called subscriber, the testwire of the line will be crossed or connected with the line called through the medium of the plug in the usuoil manner; but there will be no connection be tween the line of the subscriber who sentin the cell and the test-wire of said line, because the springjuck of thelineol the calling subscriber will not be used in making the connection beo-tween the two subscribers. Hence, the testwire of the calling subscriber would be left on tirely disconnected, and there would he no means of testing at the different boards to determine whether a line having its plug in- 5 sorted in the switch of another line was thus busy. I

Myinvenlion consists in providing a switching device and connection for each of the different tcst-circnits, so that on taking up the 5o plug of any line the test circuit or wire of said l battery of the operator. This connection with I00 line will be immediately closed to ground, so that an operator at any other board, on connecting with the said test-wire at any other board, will find circuit, and will thus know that the line is busy.

My invention also consists in cerluin modifications in the listening hey, whereby the listening key may he used as n culling-key.

As to the state of the art prior to my invention reference is rustle to United States Letters Patent No. 305,021., of September 9, 1884, and No. 806,414, oi October 14, 1854.

My invention is illustrated in the accompanying drawing, in which I have shown sections of two multiple switch-boards, each pro vided with Spring jacks for two lines, the lines connected therewith, the tcst-circuiis, and the grouudconnection, which I have invented.

The telephone-lined passes through uswitch on each of the boards, and from the switch on the lust heard through an unnuncintor and listening-hey, and thence through acord and plug to switch 5, and thence to ground. The other telephone-line, 0, passes in like manner across the boards through its annunciutor, 7 5 listeninghcy, and cord and plug to switch (I, and thence to ground.

The test wires or circuits 6 undf of the different lines are connected in the usual way with insulated frames or test-pieces of the switches. A plug inserted in any switch connects the frame, and hence the test-wire, with the telephone-line, and thus at test made at a switch of the line on any other board will show that the line is busy, as is shown in the well-known multiple switch-board system claimed in my said Patent No. 305,021, of September 9, 1881. As only one plug is used in connecting two lines, it is necessary to provide means for testing the line whose plug is inserted in the other line. This I accomplish by providing groundconnections 9 g for the different test-wires. hen a plug, 11, is lifted, the switch b closes upon the point of ground-wire 9, end thus the test-wire e is connected to ground. The fact that it is thus connected may be readily determined by touching the test-plate of any switch of that line at any board with the test-plug connected in circuit with the telephone and the test-plate of a busy line at any board will give a click in the operators telephone to indicate that the test-plate is grounded, and hence that the line is busy.

At board No. 1 I have shown the cam-lever of the listening and calling key in its upright position, in which the plunger is in its intermediate position. In this position the circuit of the telephone-line is closed between the springs 76 Z through the medium of the plunger. This is the normal position of the plunger when the telephone-line is not in use, and also when the telephoneline is connected with another line.

At board No. 2 I haveshown the cam-lever turned to the right, so as to raise the plunger to its highest position. The plunger is thus disconnected from both springs of the switch, and the springs, by their own resiliency, close upon the contact-points m it, thus looping the operators telephone into circuit. when the cam-lever is in this position, the switch is used as a listening-key.

On one of the springs of each switch I have provided the insulation 0,and below the springs a contact-poiut,p. On throwing the canrlever to the left the plunger is forced down, so as to impinge against the insulating material 0 and close upon contact-pointp. In this position the circuit of the generator q may be traced to the plunger, thence to the spring of the switch with which the cord is connected, (not to the other spring because of the insulation 0,) and thence, when the plug is inserted, to the line of the subscriber called. Thus the called subscriber may be summoned.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. In a multiple-switchboard system of tele phone-exchange, the combination, with telepone-lines connected with different switches upon the different boards, of test-circuits, one for each telephoneline, connected with the insulated frames or testpieces of the switches of their diflerentlines, respectively, and groundconnections 5/ 9, connected with the diderent test-circuits and switches 11 d, operated by the plugs, whereby the different test-wires are connected to ground, substantially as shown and described.

2. In a multiple-switch-board system of telephone-exchange, the combination, with a telephone-line, a, which is connected with the switch on each of the boards and through an aununciator, listeningkey, cord and plug, and switching device to ground, of a testcircuit, a, connected with the test-plates of the different switches of said line, and a groundconncction, g, whereby said test-wireis antomaticthe plunger impinges when forced to itslowest position, and the contact-point 19, upon which the plunger closes, substantially as shown and described.

In witness whereof I hereunto subscribe my name this 1st day of November, A. D. 1886.

ERNEST P. \VARNER.

XVitnesses:

GEORGE P. BARTON, Ones. G. ivoonwonrn. 

